WCF error: There was an error while trying to serialize parameter http://microsoft.synchronization:sourceChanges

Question

I get the error message when use sync custom provider to sync remote folder use WCF .

I get this error when the code line below is called inside of the GetChange(ChangeBatch sourcechanges)

service.GetChange(folderPath,sourcechanges)

Error message is:

There was an error while trying to serialize parameter http://microsoft.synchronization:sourceChanges. The InnerException message was 'Type 'Microsoft.Synchronization.SyncIdFormatGroup' with data contract name 'SyncIdFormatGroup:http://schemas.datacontract.org/2004/07/Microsoft.Synchronization'
is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.'.
Please see InnerException for more details.